DIY CNC router project

Motors and driver chips arrived in a package with some stuff for other projects today. Can`t find much information about the motors online and they have some marks on the body but they should work great. I`ll breadboard a circuit up to test the motors later.

I drew up a base and gantry in sketchup. Both are made of 15mm MDF. I went through a few different versions of the Y and Z axis trying to waste less space and make it more resistant to inaccuracies in my cutting. Originally the Y was 2 steel bars with adjustion blocks but I couldnt find anything suitable for rails at my hardware shop. Currently it looks like this but could change at the drop of a hat.

This was my first attempt at the Z axis carriages. Turned out pretty good and rolls as smooth as butter on aluminium.

There will be a new blog post when I actually start building the base.

04/05 Update

Slides and bearings arrived! Its actually all recycled stuff but I could never tell from the condition its in. The slides are high quality super solid draw slides with ball bearings. Fully extended and not even a fraction of a mm slop - Im a happy chappy :D Of course they only extend 200mm but its enough for my purposes.

I only got 10 ball bearings this time because I wasnt sure if they would be too small. I think they will *just* do so I`ll have to get a bunch more. At the back is one with an m5 bolt through.

So the weather is getting warmer here and I`m finally finding the motivation to get out from under my cosy and warm kotatsu to do some building when I notice the parts website I usually use has some big stepping motors for cheap. What else does some do with steppers but build a CNC machine of course! This will be my first but I`ve been checking out peoples home made machines for years always dreaming of one.

The ultimate goal is to have the machine cut foam, plastics, wood and aluminium and eventually add a 4th rotational axis so I can engrave pens and cups etc. The bed will be small, maybe a travel of 300x200mm x/y and the z axis about 200mm, that way I don`t have to worry too much about sag and I can send it home in a crate when I move back to Australia in november.

Ideally it will be a moving gantry style so if I want to do longer stuff I can just have it hang over the sides. The bed will be made of MDF and the frame made of 20mm square aluminium tube. I have some used slides in the mail for the gantry to sit on and a bunch of bearings to make a Y rail with. I`m still thinking about the Z axis. I want to get my hands on these slides before I do too much planning.

For now it will all be driven by hardware store threaded rod and some nuts pushed apart with a springto get rid of backlash. The motors should have oodles of torque that they can deal with it. If the rest of the machine turns out OK I can upgrade to acme or ball screws in the future.

I`ll cook up the electronics myself too (anything to keep the cost down) and drive it with an atmega32

I`d love to be able to throw down $1000 for a kit of the good stuff but thats more than we can afford right now. Plus it`s only my first machine so I wanted to make it myself and learn how they work in the process. If I find myself using it all the time and wishing it was more accurate or powerful I`ll have to beg steal or borrow the money from my wife.

Looks like a pretty standard design. The weak point is the drawer slides. They are nortoriously sloppy under force and not suitible for fine work. Drill rods and bronze bearings are better, linear slides are best (but very expensive). Also, consider thebuild up of debris inside the slides. For all the building effort, consider upgrading.

Be very exact when drilling the holes for the bearing, again inaccuracy will haunt you later. When building a CNC, there are no dimensions that are just "good enough".